New research proves that there is such a thing as "beauty sleep," after finding that just 2 nights of poor sleep can make one appear less attractive and healthy to others.

Researchers say that just 2 nights of sleep deprivation can make one appear less attractive.

Furthermore, researchers found that reduced attractiveness caused by lack of sleep may impact a person's social life; people may be less willing to socialize with individuals who fail to get enough shuteye.

Study co-author Dr. Tina Sundelin, of the Department of Clinical Neuroscience at the Karolinska Institutet in Sweden, and colleagues recently reported their findings in the journal Royal Society Open Science.

We all know that sleep is essential for our health and well-being. Not only is it important for memory consolidation, but our bodies also need sleep in order to restore and rejuvenate.

However, statistics show that around 1 in 3 adults in the United States fail to get the recommended minimum of 7 hours of sleep each night.

Unsurprisingly, insufficient sleep can take its toll on our appearance, with puffy eyes and a dull complexion being two of the tell-tale signs of a bad night's slumber - and, according to the new study, these effects do not go unnoticed by others.

Sleep-deprived adults rated as less attractive and healthy

Sundelin and colleagues enrolled 25 healthy men and women to their study.

Each participant was required to sleep for 8 hours on 2 consecutive nights. One week later, subjects were asked to restrict their sleep to just 4 hours on 2 consecutive nights.

After both sleep conditions, participants visited a laboratory to have their photograph taken. For the photographs, subjects were instructed not to wear makeup, to wear their hair pulled away from their faces, and to wear a gray t-shirt.

Next, the researchers recruited 122 adults - referred to as "raters" - and asked them view each photograph. The adults were asked to rate how attractive, healthy, or trustworthy they perceived the person in each photograph to be, as well as whether they would like to socialize with that person.

Not only were participants rated as less attractive and healthy following sleep restriction than when they were well rested, but the raters also reported a reduced willingness to socialize with adults who looked sleep-deprived.

Ratings of trustworthiness did not appear to be affected by sleep duration, the team reports.

Findings may be explained by effects of sleep on blood flow to the skin

Sundelin and colleagues speculate that the effect of sleep deprivation on skin blood coloration may partly explain why poorly rested adults were rated less attractive and healthy.

"A healthy, attractive face is characterized by a certain degree of redness, which in turn is indicative of increased vasodilation and vascularization," they write.

"Blood flow to the skin is strongly promoted by sleep and this vasodilation may be a way for the body to facilitate the distribution of endogenous defense agents. With a lack of sleep, blood flow to the skin is reduced, and according to raters faces look more pale after not sleeping."

While further studies are needed to gain a better understanding of the mechanisms underlying the effects of sleep deprivation on facial appearance, the researchers believe that their findings further highlight the importance of a good night's sleep.

It also adds to previous studies on facial appearance after sleep loss, showing that despite using a different scale, and a less substantial and more natural sleep-loss condition, the relationships between sleep, attractiveness and a healthy appearance still hold."